July 6th, 2012 by Michael Ricciardi
For the first time, a key component of the mostly “hidden” but large-scale structure of the Universe has been observed by a team of astronomers at the University of Munich Observatory in Germany. The team, lead by Jörg Dietrich, was able to directly observe a “dark matter tendril” or “filament” — gigantic structures that (it is theorized) extend throughout the Universe. These vast, low-density structures intersect where galaxy clusters tend to occur.
The discovery — nearly overlooked due to the anticipation and speculation around the possible discovery of the Higgs Boson — marks the first time scientists have observationally verified this very important theoretical prediction (the clues to which were made by Australian grad student Amelia Fraser-McKelvie while conducting an x-ray survey just over a year ago).
These massive, large-scale cosmic structures may account for the “missing mass” predicted to exist by Cal Tech astronomer Fritz Zwicky in 1933 (representing over 80% of the material universe).
Due to their low density, the filaments are very difficult to observe. But the team was able to directly observe one such massive filament due to a bit of luck: its perpendicular orientation to Earth. This orientation makes it slightly more dense in appearance from our cosmic perspective.
And, due to an effect known as gravitational lensing, the structure deforms the light from objects “behind” it. By observing this lensing over a span of 40,000 background galaxies, the astronomers were able to calculate the mass of the filament to be between 6.5 × 10^13 and 9.8 × 10^13 times the mass of the Sun.
The huge dark matter tendril is 18 megaparsecs long and connects (“bridges”) two galaxy clusters — Abell 222 and Abell 223 — located 2.7 billion light-years away in the constellation Cetus.
The discovery will help astronomers and astrophysicists determine how visible matter interacts with dark matter to form galaxies.
The results of this study were published in the journal Nature last Wednesday, June 27.
Read more about this discovery on the Gizmodo website.
Top image: (dark matter filaments) University of Munich Observatory (Dietrich et al) and Nature via the Gizmodo site (see link above).
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